Phantom limb pain is a neuropathic condition affecting amputees. It
occurs when damaged nerves at the site of the amputation continue to
send signals to the brain, causing the amputee to think the missing body
part is still there. Although phantom limb pain usually occurs after the
amputation of an arm or leg, it can appear in any area of amputation,
and discomfort can include not just pain but cold, heat, cramping, or
any other common sensation.
Incidence and Current Treatments
It’s estimated that phantom limb pain affects 50 to 80 percent of all
amputees. The condition usually occurs during the first year after the
amputation and often becomes chronic, lasting for months or even years
with either no improvement or an increase in pain. Amputees may suffer
from phantom limb pain their entire lives.
Veterans are one of the largest groups to experience amputations, with
the wars in Iraq and Afghanistan alone resulting in 1,715 amputations as
of January 2013. For them, and for other amputees, phantom limb pain can
be devastating. Current treatment is a matter of trial and error, with
little relief experienced by most patients. A 1984 survey of 5,000 U.S.
amputee veterans found that
78 percent suffered from phantom limb syndrome, but a scant 1 percent
experienced any relief through treatment.
Medical Marijuana as a Treatment
In 2007, Health Canada approved Sativex, a whole-plant-derived cannabis
extract, for the treatment of HIV-related neuropathic pain. While
Sativex it is not currently available in the United States, it is in the
process of FDA approval. Although not completely understood, the
mechanism of action seems to be that cannabinoids work on specific pain
receptors as well as the neurons that transmit pain.
In the United States, medical marijuana as a treatment for neuropathic
pain has been the subject of much research. A 2007 study published in
"Neurology" found that
smoked cannabis reduced patients’ pain by 30 percent over the course of
only five days, and over three dozen preclinical and clinical
trials have validated this
finding. Cannabinoids act as a sort of circuit-breaker, binding to pain
receptors and stopping the production of neurotransmitters which carry
pain signals. They therefore provide some relief from chronic
neuropathic pain, including the pain involved in phantom limb syndrome.